Wireless timing and power control

ABSTRACT

The use of multiple states of mobile communication device operation to allow a single base station to support a relatively large number of mobile nodes is described. The various states require different amounts of communications resources, e.g., bandwidth. Four supported states of operation are an on-state, a hold-state, a sleep-state, and an access-state. Each mobile node in the on-state is allocated communication resources to perform transmission power control signaling, transmission timing control signaling and to transmit data as part of a data uplink communications operation. Each mobile node in the hold-state is allocated communication resources to perform transmission timing control signaling and is provided a dedicated uplink for requesting a state transition and a shared resource for transmitting acknowledgements. In the sleep state a mobile node is allocated minimal resources and does not conduct power control signaling or timing control signaling. Data may be received in the on and hold states.

RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/324,194 filed Dec. 20, 2002 titled “Methods andApparatus for Operating Mobile Nodes in Multiple States” and acontinuation-in-part of U.S. patent application Ser. No. 10/378,563filed Mar. 3, 2003 titled “Methods and Apparatus for Operating MobileNodes in Multiple States” and claims the benefit of U.S. ProvisionalPatent Application S.N. 60/401,920 filed on Aug. 8, 2002, titled“Methods and Apparatus for Implementing Mobile Communications System”each of which is hereby expressly incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention is directed to wireless communicationssystems and, more particularly, to methods and apparatus for supportinga plurality of mobile nodes in a communications cell with limitedresources.

BACKGROUND OF THE INVENTION

[0003] Wireless communications systems are frequently implemented as oneor more communications cells. Each cell normally includes a base stationwhich supports communications with mobile nodes that are located in, orenter, the communications range of the cell's base station. Within acell or a sector of a cell, the unit of communications resource is asymbol, e.g., QPSK or QAM transmitted on one frequency tone for one timeslot in an orthogonal frequency division multiplexed (OFDM) system. Thetotal available communication resource is divided into a number of suchsymbols (units) which can be used for communicating control and datainformation between a base station and one or more mobile nodes in thecell and tends to be limited. Control signals transmitted between abasestation and a mobile node may be transmitted in two possibledirections, i.e., from the basestation to the mobile node or from themobile node to the base station. Transmission of signals from the basestation to the mobile is often called a downlink. In contrast,transmission from the mobile to the base station is commonly referred toas an uplink.

[0004] In order to provide efficient use of limited communicationsresources, base stations may allocate different numbers of tones todifferent mobile nodes depending on the devices' bandwidth needs. In amultiple access system, several nodes may be transmitting data, e.g., inthe form of symbols, to a base station at the same time using differenttones. This is common in OFDM systems. In such systems, it is importantthat symbols from different mobile nodes arrive at the base station in asynchronized manner, e.g., so the base station can properly determinethe symbol period to which a received symbol belongs and signals fromdifferent mobile nodes do not interfere with each other. As mobile nodesmove in a cell, transmission delay will vary as a function of thedistance between a mobile node and a base station. In order to make surethat transmitted symbols will arrive at a base station from differentmobile nodes in synchronized manner, timing control signals, e.g.,feedback signals, may be and in many cases are, transmitted to eachactive mobile node of a cellular system. The timing control signals areoften specific to each device and represent, e.g., timing corrections ofoffsets to be used by the device to determine symbol transmissiontiming. Timing control signaling operations include, e.g., monitoringfor timing control signals, decoding received timing control signals,and performing timing control update operations in response to thedecoded received timing control signals.

[0005] Timing control signals can be particularly important in systemswhere there are a large number of mobile nodes. In order to avoidinterference from a mobile node due to timing miss synchronization, itmay be necessary to establish timing synchronization and control beforeallowing a mobile node to transmit data, e.g., voice data, IP packetsincluding data, etc. to a base station.

[0006] In addition to managing limited resources such as bandwidth,power management is often a concern in wireless communications systems.Mobile nodes, e.g., wireless terminals, are often powered by batteries.Since battery power is limited, it is desirable to reduce powerrequirements and thereby increase the amount of time a mobile node canoperate without a battery recharge or battery replacement. In order tominimize power consumption, it is desirable to limit the amount of powerused to transmit signals to a base station to the minimal amount ofpower required. Another advantage of minimizing mobile node transmissionpower is that it has the additional benefit of limiting the amount ofinterference that the transmissions will cause in neighboring cellswhich will often use the same frequencies as an adjoining cell.

[0007] In order to facilitate transmission power control, power controlsignaling, e.g., a feedback loop, may be established between a basestation and a mobile node. Power control signaling often takes place ata much faster rate than the timing control signaling. This is becausepower control signaling attempts to track variations in the signalstrength between the base station and the mobile nodes and this cantypically vary on the scale of milliseconds. The timing control needs totake into consideration changes in the distance between base station andthe mobile nodes and this tends to vary on a much slower scale,typically hundreds of milliseconds to seconds. Thus the amount ofcontrol signaling overhead for power control tends to be much more thanthat for timing control.

[0008] In addition to timing and power control signaling, other types ofsignaling may be employed. For example mobile nodes in addition may alsosignal on an uplink the quality of the downlink channel. This may beused by the base station to determine the communication resourceallocation to allow for the transfer of data packets from the basestation to the mobile. Such downlink channel quality reports allows abase station to determine which mobile node to transmit to and if amobile node is chosen then the amount of forward error correctionprotection to apply to the data. These downlink channel quality reportsgenerally are signaled on a similar time scale as the power controlsignaling. As another example, signaling may be used to periodicallyannounce a mobile node's presence in a cell to a base station. It canalso be used to request allocation of uplink resources, e.g., totransmit user data in a communications session. Shared as opposed todedicated resources may be used for such announcements and/or resourcerequests.

[0009] Signaling resources, e.g., time slots or tones, may be shared ordedicated. In the case of shared time slots or tones, multiple devicesmay attempt to use the resource, e.g., segment or time slot, tocommunicate information at the same time. In the case of a sharedresource, each ode in the system normally tries to use the resource onan as needed basis. This sometimes results in collisions. In the case ofdedicated resources, e.g., with time slots and/or tones being allocatedto particular communications device or group of devices to the exclusionof other devices for a certain period of time, the problem of possiblecollisions is avoided or reduced. The dedicated resources may be part ofa common resource, e.g., a common channel, where segments of the channelare dedicated, e.g., allocated, to individual devices or groups ofdevices where the groups include fewer than the total number of mobilenodes in a cell. For example, in the case of an uplink time segments maybe dedicated to individual mobile nodes to prevent the possibility ofcollisions. In the case of a downlink, time slots may be dedicated toindividual devices or, in the case of multicast messages or controlsignals, to a group of devices which are to receive the same messagesand/or control signals. While segments of a common channel may bededicated to individual nodes at different times, over time multiplenodes will use different segments of the channel thereby making theoverall channel common to multiple nodes.

[0010] A logical control channel dedicated to an individual mobile nodemay be comprised of segments of a common channel dedicated for use bythe individual mobile node.

[0011] Dedicated resources that go unused may be wasteful. However,shared uplink resources which may be accessed by multiple userssimultaneously may suffer from a large number of collisions leading towasted bandwidth and resulting in an unpredictable amount of timerequired to communicate.

[0012] While timing and power control signals and downlink channelquality reports are useful in managing communications in a wirelesscommunications system, due to limited resources it may not be possiblefor a base station to support a large number of nodes when powercontrol, and other types of signaling need to be supported on acontinuous basis for each node in the system.

[0013] In view of the above discussion, it is apparent that there is aneed for improved methods of allocating limited resources to mobilenodes to permit a relatively large number of nodes to be supported by asingle base station with limited communications resources. It isdesirable that at least some methods of communications resourceallocation and mobile node management take into consideration the needfor timing control signaling and the desirability of power controlsignaling in mobile communications systems.

SUMMARY OF THE INVENTION

[0014] The present invention is directed to methods and apparatus forsupporting multiple wireless terminals, e.g., mobile nodes, using asingle base station and limited resources such as bandwidth for thetransmission of signals between the base station and mobile nodes, e.g.,in a communications cell. A system may be implemented in accordance withthe invention as a plurality of cells, each cell including at least onebase station which serves multiple mobile nodes. A mobile node can, butneed not, move within a cell or between cells.

[0015] In accordance with the present invention, mobile nodes supportmultiple states of operation. The control signaling resources used by amobile node vary depending on the state of operation. Thus, depending onthe state of the mobile node, a large amount of signaling resources maybe required while in other states a minimum amount of resources may berequired. Control signaling resources are in addition to datatransmission resources, e.g., bandwidth used to communicate payload datasuch as voice, data files, etc. By supporting different mobile nodestates of operation, requiring differing amounts of base station/mobilenode control communications resources, e.g., signal bandwidth, used forcontrol purposes, more mobile nodes can be supported by a base stationthan could be supported if all mobile nodes were allocated the sameamount of communications resources for control signaling purposes.

[0016] Bandwidth allocated to a particular mobile device forcommunicating control signals between the mobile device and a basestation is known as dedicated control bandwidth. Dedicated controlbandwidth may comprise multiple dedicated logical or physical controlchannels. In some embodiments, each dedicated control channelcorresponds to one or more dedicated segments of a common controlchannel. Control channel segments may be, e.g., channel time slots usedfor transmitting and/or receiving control signals. Dedicated uplinkcontrol channel segments differ from shared uplink control channelsegments where multiple devices share the same bandwidth for uplinksignaling.

[0017] In the case of a shared communications channel conflicts mayresult when multiple nodes, at the same time attempt to transmit acontrol signal using the shared communications channel.

[0018] Mobile nodes implemented in accordance with one exemplaryembodiment support four states, e.g. modes of operation. The four statesare a sleep state, a hold state, an access state, and an on state. Ofthese the access state is a transitory stage and the other states aresteady states and the mobile nodes can be in these states for anextended period of time.

[0019] Of the four states, the on state requires the highest amount ofcontrol signaling resources, e.g., bandwidth used for control signalingpurposes. In this state, the mobile node is allocated bandwidth on asneeded basis for transmitting and receiving traffic data, e.g., payloadinformation such as text or video. Thus, at any given time in the onstate a mobile node may be allocated a dedicated data channel fortransmitting payload information. In the on state the mobile node isalso allocated a dedicated uplink control signaling channel.

[0020] In various embodiments, a dedicated uplink control channel isused during the on state by the MN to make downlink channel qualityreports, communicate resource requests, implement session signaling,etc. Downlink channel quality reports are normally signaled frequentlyenough to track variations in the signal strength between the basestation and the mobile node.

[0021] During the on state, the base station and mobile node exchangetiming control signals using one or more dedicated control channelsallowing the mobile node to periodically adjust its transmission timing,e.g., symbol timing, to take into consideration changes in distance andother factors which might cause the transmitted signals to drift timingfrom the base station's perspective, with the signals transmitted byother mobile nodes. As discussed above, the use of timing controlsignaling and performing timing control signaling operations, such asupdating transmission timing, is important in many systems which useorthogonal frequency division multiple access in the uplink to avoidinterference from transmission signals generated by multiple nodes inthe same cell.

[0022] To provide transmission power control, during the on state,transmission power control signaling is employed to provide a feedbackmechanism whereby a mobile node is able to efficiently control itstransmission power levels based on signals periodically received fromthe base station with which it is communicating. In various embodimentsthe base station periodically transmits power control signals over adedicated control downlink. As part of the transmission power controlsignaling process, the mobile node, performs various transmission powercontrol signaling operations including, for example, monitoring fortransmission power control signals directed to the particular mobilenode, decoding received transmission power control signals, and updatingits transmission power levels based on the received and decodedtransmission power control signals. Thus, in response to receiving powercontrol signals in a dedicated downlink segment corresponding to theparticular mobile node, the mobile node adjusts its transmission powerlevel in response to the received signal. In this manner, a mobile nodecan increase or decease its transmission power to provide for successfulreceipt of signals by the base station without excessive wastage ofpower and therefore reducing interference and improving battery life.The power control signaling is typically carried out sufficientlyfrequently to track fast variations in the signal strength between thebase station and the mobile nodes. The power control interval is afunction of smallest channel coherence time that the system is designedfor. The power control signaling and the downlink channel qualityreports are normally of similar time scale, and in general, occur at amuch higher frequency than the timing control signaling. However, inaccordance with one feature of the present invention the base stationvaries the rate at which it transmits power control signals to a mobilenode as a function of the mobile node's state of operation. As a result,in such an embodiment, the rate at which the mobile node performstransmission power control adjustments will vary as a function of thestate in which the mobile node operates. In one exemplary embodiment,power control updates are not performed in the sleep state and, whenperformed in the hold state, are normally performed at a lower rate thanduring the on state.

[0023] Operation of a mobile node in the hold state requires fewercontrol communications resources, e.g., bandwidth, than are required tosupport operation of a mobile node in the on state. In addition, invarious embodiments while in the hold state a mobile node is deniedbandwidth for transmitting payload data, but the mobile can be allocatedbandwidth for receiving payload data. In such embodiments the mobilenode is denied a dedicated data uplink communications channel during thehold state. The bandwidth allocated for receiving data may be, e.g., adata downlink channel shared with other mobile nodes. During the holdstate timing control signaling is maintained and the mobile node is alsoallocated a dedicated control uplink communication resource, e.g.,dedicated uplink control communications channel, which it can use torequest changes to other states. This allows, for example, a mobile nodeto obtain additional communications resources by requesting a transitionto the on state where it could transmit payload data. In some but notall embodiments, in the hold state, the dedicated uplink control channelis limited to the communication of signals requesting permission tochange the state of mobile node operation, e.g., from the hold state tothe on state. During the hold state the bandwidth allocated, e.g.,dedicated, to a mobile node for control signaling purposes is less thanin the on-state.

[0024] Maintaining timing control while in the hold-state allows themobile nodes to transmit their uplink requests without generatinginterference to other mobiles within the same cell and having adedicated uplink control resource ensures that the delays for statetransition are minimal as the requests for state transitions do notcollide with similar requests from other mobile nodes as may occur inthe case of shared uplink resources. Since timing control signaling ismaintained, when the mobile node transitions from the hold state to theon state it can transmit data without much delay, e.g., as soon as therequested uplink resource is granted, without concerns about creatinginterference for other mobile nodes in the cell due to drift of uplinksymbol timing. During the hold state, transmission power controlsignaling may be discontinued or performed less frequently, e.g., atgreater intervals than performed during on state operation. In thismanner, the dedicated control resources used for power control signalingcan be eliminated or reduced allowing fewer resources to be dedicated tothis purpose than would be possible if power control signaling for allnodes in the hold state was performed at the same rate as in the onstate.

[0025] When transitioning from the hold state to the on state, themobile node may start off with an initial high power level to insurethat its signals are received by the base station with the power levelbeing reduced once transmission power control signaling resumes at anormal rate as part of on state operation. In one exemplary embodiment,when the mobile node in the hold state intends to migrate to the onstate, it transmits a state transition request using a dedicated uplinkcommunication resource, which is not shared with any other mobile nodes.The base station then responds with a broadcast message indicating itsresponse to the mobile's state transition request. The mobile onreceiving the base station message meant for it responds with anacknowledgement. The acknowledgment is transmitted over a sharedresource on the uplink and is slaved to the broadcast message on thedownlink.

[0026] By transmitting an appropriate state transition request themobile may also transition to the sleep state. In one exemplaryembodiment, when the mobile node does not intend to migrate to anotherstate, the mobile node may not transmit any signal in its dedicateduplink communication channel, though the dedicated channel has beenassigned to the mobile node and is therefore not used by any othermobile nodes. In another embodiment, the mobile node uses an on/offsignaling in its dedicated uplink communication channel, where themobile node sends a fixed signal (on) when it intends to migrate toanother state and does not send any signal (off) when it does not intendto migrate to any other state. In this case, the transmission of thefixed signal can be interpreted as a migration request to the on stateif the transmission occurs at certain time instances, and as a migrationrequest to the sleep state if the transmission occurs at some other timeinstances.

[0027] In order to support a large number of mobile nodes, a sleep staterequiring relatively few communications resources is also supported. Inan exemplary embodiment, during the sleep state, timing control signaland power control signaling are not supported. Thus, in the sleep state,the mobile nodes normally do not performing transmission timing controlor transmission power control signaling operations such as receiving,decoding and using timing and transmission power control signals. Inaddition, the mobile node is not allocated a dedicated uplink controlresource, e.g., uplink control communications channel, for making statetransition requests or payload transmission requests. In addition,during the sleep state the mobile node is not allocated datatransmission resources, e.g., dedicated bandwidth, for use intransmitting payload data, e.g., as part of a communications sessionwith another node conducted through the base station.

[0028] Given the absence of a dedicated uplink control channel duringthe sleep state, a shared communications channel is used to contact thebase station to request resources necessary for a mobile node toinitiate transition from the sleep state to another state.

[0029] In some embodiments, in the sleep state the mobile node may, atthe behest of the base station serving the cell, signal its presence inthe cell, e.g., using a shared communications resource. However, asdiscussed above, little other signaling is supported during this stateof operation. Thus, very little control signaling bandwidth is used tocommunicate control information between mobile nodes in the sleep stateand a base station serving the nodes.

[0030] The access state is a state through which a node in the sleepstate can transition into one of the other supported states. Thetransition between states may be triggered by an action by a user of themobile node, e.g., an attempt to transmit data to another mobile node.Upon entering the access state, transmission power control and timingcontrol signaling has not yet been established. During access stateoperation, timing control signaling is established and, in variousembodiments, full or partial transmission power control signaling isestablished. A mobile node can transition from the access state toeither the on state or the hold state.

[0031] The establishment of the timing synchronization and transmissionpower control can take some amount of time during which data transitionis delayed. Also the access process happens through a shared media andcontentions between mobile nodes need to be resolved. By supporting ahold state in accordance with the present invention, in addition to asleep state, such delays can be avoided for a number of mobile nodes, astransition from the hold state to the on state does not go through theaccess state, while the number of nodes which can be supported by asingle base station is larger than would be possible without the use ofreduced signaling states of mobile node operation.

[0032] In some embodiments, for an individual cell, the maximum numberof mobile nodes that can be in the sleep state at any given time is setto be greater than the maximum number of mobile nodes that can be in thehold state at given time. In addition, the maximum number of mobilenodes which can be in the hold at any given time is set to be greaterthan the maximum number of nodes that can be in the on state at anygiven time.

[0033] In accordance with a power conservation feature of the presentinvention, downlink control signaling from the base station to themobile nodes is divided into a plurality of control channels. Adifferent number of downlink control channels are monitored by a mobilenode depending on the node's state of operation. During the on state thegreatest number of downlink control channels are monitored. During thehold state a smaller number of downlink control channels are monitoredthan during the on state. In the sleep state the smallest number ofdownlink control channels are monitored.

[0034] To further reduce power consumption in the mobile node associatedwith monitoring for control signals, in accordance with one feature ofthe invention control channels monitored during the hold and sleepstates are implemented as periodic control channels. That is, signalsare not broadcast on a continuous basis on the control channelsmonitored in the hold and sleep states. Thus, during the hold and sleepstates the mobiles monitor for control signals at periodic intervals andsave power by not monitoring for control signals at those times whencontrol signals are not transmitted on the monitored channels. Tofurther decrease the time a particular mobile needs to monitor forcontrol signals during the hold and sleep states, portions, e.g.,segments, of the periodic control channels may be dedicated to one or agroup of mobile nodes. The mobile nodes are made aware of which controlchannel segments are dedicated to them and then monitor the dedicatedsegments as opposed to all the segments in the control channels. Thisallows monitoring for control signals to be performed in the hold andsleep states by individual mobile nodes at greater periodic intervalsthan would be possible if the mobile were required to monitor allsegments of the periodic control channels.

[0035] In one particular embodiment, during the on state, mobile nodesmonitor segments of an assignment channel on a continuous basis and alsomonitor segments of periodic fast paging and slow paging controlchannels. When in the hold state the mobiles monitor the fast paging andslow paging control channels. Such monitoring may involve monitoring asubset of the segments of the periodic fast and slow paging channels,e.g., segments dedicated to the particular mobile node. During the holdstate in the particular exemplary embodiment the slow paging channel ismonitored but not the fast paging channel or the assignment channel. Thepaging control channels may be used to instruct the mobile node tochange states.

[0036] By limiting the number of control channels and the rate ofcontrol channel monitoring as a function of the state of operation,power resources can be conserved in accordance with the invention whileoperating in the hold and sleep states.

[0037] The performing of both timing and power control is not requiredand, depending on the communications techniques used, both timing andpower control may not be implemented. In such a case, multiple statesmay be implemented in accordance with the invention, with the unusedtype control, e.g., power or timing, and the associated signaling, beingomitted from the implementation of the various states of operation.

[0038] In various embodiments of the present invention different levelsof power and/or timing control signaling are supported in each of atleast three different states. In one case, power and timing control areperformed in a first state, e.g., an on-state. Power control signalingis performed at a first power control rate in said on state using afirst set of power control signaling resources. Timing control is alsoperformed in said on-state at a first timing control rate using a firstset of timing control resources. In a second state, e.g., a hold state,timing and/or power control signaling is performed. These operations areperformed at a rate lower than the rate at which they are performed inthe on-state or not at all. The control signaling resources, e.g., powercontrol and timing control signaling resources, if any, used in the holdstate may and sometimes are a subset of the resources used for the sametype of signaling in the on state. In a third state, e.g., a sleepstate, timing and/or power control signaling is not performed or, ifperformed, is performed at a lower rate than in the hold state. Theseoperations, if performed, are at a rate lower than the rate at whichthey are performed in the on-state or not at all. The control signalingresources, e.g., power control and timing control signaling resources,if any, used in the sleep state may, and sometimes are, a subset of theresources used for the same type of signaling in the sleep state. Powercontrol and/or timing control may be performed in some states at thesame rate as in the more active state as long as at least one of powercontrol and timing control is performed at a lower rate than in the moreactive state. In some embodiments, the set of control signalingresources used in each of the states for power control signaling is asubset of the resources used in the on-state. The sleep state may use asubset of the power control signaling resources used in the hold stateor none at all. In some embodiments, the set of control signalingresources used in each of the states for timing control signaling is asubset of the timing control signaling resources used in the on-state.The sleep state may use a subset of the timing control signalingresources used in the hold state or none at all.

[0039] Unlike some other known systems, a wireless terminal implementedin accordance with the invention may remain in a hold or sleep state forextended periods of time, e.g., many milliseconds, e.g., 10 or moremilliseconds, without transmitting any signals. This offers significantpower advantages over other systems where timing and/or power controlsignaling rates must be maintained at far more frequent intervals.

[0040] Wireless terminal transitions between states may be controlled asa function of Quality of service information associated with one or morewireless terminals and/or quality of service information of the trafficassociated with one or more wireless terminals. In this manner,different levels of quality of service may be provided to differentdevices or different traffic, in part, by controlling the transition ofdevices between states, e.g., to manage allocation of availableresources in a cell to provide different devices or traffic withdifferent quality of service levels. The wireless terminals and/or basestations in a cell may store quality of service profile information forpurposes of the information being used as in input to a routine whichcontrols state transitions.

[0041] Transitions between states, or requests to transition betweenstates, may be triggered by input from a wireless terminal user, e.g.,an attempt by a user to send or receive data by pressing a button orother input device on the wireless terminal.

[0042] In one particular exemplary implementation of a communicationsmethod implemented in accordance with the invention, a wireless terminalis operated at different times, in each one of at least three differentoperational states, the three different operational states including afirst state, a second state and a third state. While operating in thefirst state the wireless terminal uses a first amount of a controlcommunications resource used to send control signals between a basestation and the wireless terminal. While operating in the second statethe wireless terminal uses a second amount of the control communicationsresource, the second amount of the control communications resource beingless than the first amount. The second amount of the controlcommunications resource includes, in various embodiments, a dedicateduplink signaling channel and a shared downlink signaling channel used tocommunicate information relating to the allocation of uplink anddownlink resources for the communication of data, respectively. Thededicated uplink channel may be formed from segments of a correspondinguplink control signaling channel which are dedicated to the wirelessterminal so that other terminals do not use the dedicated channelsegments. The shared downlink channel may be comprised of a set ofdownlink control channel segments which may be part of a downlinkcontrol channel which may include additional segments which are not usedby the particular wireless terminal. The shared downlink channel, e.g.,the segments of the downlink channel which may be used to communicateinformation may be monitored by multiple devices for information. Thus,in some embodiments, the dedicated uplink control signaling channel andshared downlink control signaling channel may be logical channelscreated from segments of larger uplink and downlink channels. In theparticular embodiment, operating the wireless terminal in the thirdstate includes using a third amount of the control communicationsresource which is less than said first and second amounts. Thetransitioning from one of said three states to another one of said threestates maybe in response to a change in user activity, e.g., entry ofinformation from a user indicating an attempt to send or receive data.In the particular exemplary embodiment said first state may be an onstate, said second state may be a hold state, and said third state maybe a sleep state. In various implementations of the particularembodiment, the third amount of control communications resourcesincludes a third set of communications elements, the second amount ofcontrol communications resource includes a second set of communicationselements which includes additional communications elements in additionto said third set of communications elements, and where the first amountof control communications resource includes a first set ofcommunications elements which includes said second set of communicationselements in addition to other communications elements. Thecommunications elements may, e.g., correspond to segments of controlsignaling communications channels used by said wireless terminal. Insome but not all implementations while operating in the second state thewireless terminal transmits at most, a small number of bits over saiduplink signaling channel during any one uplink signaling transmissionperiod. The small number of bits is, in some embodiments, at most 8bits.

[0043] Wireless terminals may be implemented as mobile nodes such asnotebook computers, personal data assistants, etc.

[0044] Numerous additional features, benefits and details of the methodsand apparatus of the present invention are described in the detaileddescription which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045]FIG. 1 illustrates an exemplary communication cell, which may bepart of a communications system, implemented in accordance with thepresent invention.

[0046]FIG. 2 illustrates a base station implemented in accordance withthe present invention.

[0047]FIG. 3 illustrates a mobile node implemented in accordance withthe present invention.

[0048]FIG. 4 is a state diagram illustrating the different states that amobile node may enter while operating in accordance with the presentinvention.

[0049]FIG. 5 is a chart illustrating various control and signalingmodules that are executed by a mobile node during each of the differentstates illustrated in FIG. 4.

[0050]FIG. 6 illustrates the transmissions associated with threeexemplary downlink control channels used in accordance with oneembodiment of the present invention.

[0051]FIG. 7 illustrates which control channels shown in FIG. 6 aremonitored in each of the four states in which a mobile node of thepresent invention may operate.

[0052]FIG. 8 is a chart illustrating various control and signalingmodules that are executed within an exemplary wireless terminal, inaccordance with the invention, for each of the three states: on, hold,sleep.

[0053]FIG. 9 illustrates exemplary uplink and downlink channels andexemplary transmission segments, corresponding to each channel, whichmay be used to transmit signal.

DETAILED DESCRIPTION

[0054]FIG. 1 illustrates a communications cell 10 implemented inaccordance with the present invention. A communications system mayinclude multiple cells of the type illustrated in FIG. 1. Thecommunications cell 10 includes a base station 12 and a plurality, e.g.,a number N, of mobile nodes 14, 16 which exchange data and signals withthe base station 12 over the air as represented by arrows 13, 15. Inaccordance with the invention, the base station 12 and mobile nodes 14,16 are capable of performing and/or maintaining control signalingindependently of data signaling, e.g., voice or other payloadinformation, being communicated. Examples of control signaling includepower control, downlink channel quality reports, and timing controlsignaling.

[0055]FIG. 2 illustrates a base station implemented in accordance withthe present invention. As shown, the exemplary BS 12 includes a receivercircuit 202, transmitter circuit 204, processor 206, memory 210 and anetwork interface 208 coupled together by a bus 207. The receivercircuit 202 is coupled to an antenna 203 for receiving signals frommobile nodes. The transmitter circuit 204 is coupled to a transmitterantenna 205 which can be used to broadcast signals to mobile nodes. Thenetwork interface 208 is used to couple the base station 12 to one ormore network elements, e.g., routers and/or the Internet. In thismanner, the base station 12 can serve as a communications elementbetween mobile nodes serviced by the base station 12 and other networkelements.

[0056] Operation of the base station 12 is controlled by the processor206 under direction of one or more routines stored in the memory 210.Memory 210 includes communications routines 223, data 220, sessionmanagement/resource allocation routine 222, session and resourcesignaling subroutine 225, and active user information 212.Communications routines 223, include various communications applicationswhich may be used to provide particular services, e.g., IP telephonyservices or interactive gaming, to one or more mobile node users. Data220 includes data to be transmitted to, or received from, one or moremobile nodes. Data 220 may include, e.g., voice data, E-mail messages,video images, game data, etc.

[0057] The session management and resource allocation routine 222operates in conjunction with subroutines 225 and active user information212 and data 220. The routine 222 is responsible for determining whetherand when mobile nodes may transition between states and also theresources allocated to a mobile node within a state. It may base itsdecision on various criteria such as, requests from mobile nodesrequesting to transition between states, idletime/time spent by a mobilein a particular state, available resources, available data, mobilepriorities etc. These criteria would allow a base station to supportdifferent quality of service (QOS) across the mobile nodes connected toit.

[0058] The session and resource signaling subroutine 225 is called bysession management routine 222 when signaling operations are required.Such signaling is used to indicate the permission to transition betweenstates. It is also used to allocate the resources, e.g., when in aparticular state. For example, in the on state a mobile node may begranted resources to transmit or receive data.

[0059] Active user information 212 includes information for each activeuser and/or mobile node serviced by the base station 12. For each mobilenode and/or user it includes a set of state information 213, 213′. Thestate information 213, 213′ includes, e.g., whether the mobile node isin an on state, a hold state, a sleep state, or an access state assupported in accordance with the present invention, number and types ofdata packets currently available for transmission to or from the mobilenode, and information on the communication resources used by the mobilenode.

[0060] Memory 210 includes quality of service (QOS) profile information221 which can be used by the session management/resource allocationroutine when making decisions about resource allocation and how tocontrol state transitions to reflect the allocation of availableresources. The base station may use the QOS profile informationassociated with one or more nodes when deciding how to control resourceallocations and/or state transitions.

[0061]FIG. 3 illustrates an exemplary mobile node 14 implemented inaccordance with the invention. The mobile node 14 includes a receiver302 coupled to an antenna 303, a transmitter 304 coupled to antenna 305,a memory 310, and a processor 306 coupled together via bus 307 as shownin FIG. 3. The mobile node uses its transmitter 306, receiver 302, andantennas 303, 305 to send and receive information to and from basestation 12.

[0062] Memory 310 includes user/device information 312, data 320, apower control and power control signaling module 322, a timing controland timing control signaling module 324, a device status control andstatus signaling module 326, a data control and data signaling module328, and QOS profile information 323 associated with the mobile nodeand/or traffic QOS profile information of the traffic associated withthe mobile node. The mobile node 14 operates under control of themodules, which are executed by the processor 306. User/deviceinformation 312 includes device information, e.g., a device identifier,a network address or a telephone number. This information can be used,by the base station 12, to identify the mobile nodes, e.g., whenassigning communications channels. The user/device information 312 alsoincludes information concerning the present state of the mobile device14. The data 320 includes, e.g., voice, text and/or other data receivedfrom, or to be transmitted to, the base station as part of acommunications session. QOS profile information 323 may be used by themobile node as in input when the processor 306 makes decisions torequest state transitions and/or to implement state transitions. Forexample, the mobile node 14 may decide to transition into a sleep statein response to detecting signals indicating resource requests from otherwireless devices in the cell which have a higher QOS associated withthem. Thus, QOS information 323 may include QOS informationcorresponding to multiple node and not just mobile node 14.

[0063] Device status control and status signaling module 326 is used fordevice status control and status signaling. Device status control module326 determines, in conjunction with signals received from the basestation 12, what mode, e.g., state, the mobile node 14 is to operate inat any given time. In response to, e.g., user input, the mobile node 14may request permission from the base station 12 to transition from onestate to another and to be granted the resources associated with a givenstate. Depending on the state of operation at any given time and thecommunications resources allocated to the mobile node 14, status controland status signaling module 326 determines what signaling is to occurand which signaling modules are to be active. In response to periods ofreduced signal activity, e.g., control signal activity, status controland status signaling module 326 may decide to transition from a currentstate of operation to a state of operation requiring fewer controlresources and/or requires less power. The module 326 may, but need not,signal the state transition to the base station. Status control andstatus signaling module 326 controls, among other things, the number ofdownlink control channels monitored during each state of operation and,in various embodiments, the rate at which one or more downlink controlchannels are monitored.

[0064] As part of the processes of controlling the state of the mobilenode 14, and overseeing general signaling between the mobile node 14 andbase station 12, the signaling module is responsible for signaling tothe base station 12, when the mobile node 14 first enters a cell and/orwhen the base station 12 requests that the mobile node 14 indicate itpresence. The mobile node 14 may use a shared communication resource tosignal its presence to the cell's base station 12, while a dedicatedcommunication resource may be used for other communication signals,e.g., uploading and downloading data files as part of a communicationsession.

[0065] Transmission power control and power control signaling module 322is used to control the generation, processing and reception oftransmission power control signals. Module 322 controls the signalingused to implement transmission power control through interaction withthe base station 12. Signals transmitted to, or received from the basestation 12 are used to control mobile node transmission power levelsunder direction of module 322. Power control is used by the base station12 and the mobile nodes 14, 16 to regulate power output whentransmitting signals. The base station 12 transmits signals to themobile nodes which are used by the mobile nodes in adjusting theirtransmission power output. The optimal level of power used to transmitsignals varies with several factors including transmission burst rate,channel conditions and distance from the base station 12, e.g., thecloser the mobile node 14 is to the base station 12, the less power themobile node 14 needs to use to transmit signals to the base station 12.Using a maximum power output for all transmissions has disadvantages,e.g., the mobile node 14 battery life is reduced, and high power outputincreases the potential of the transmitted signals causing interference,e.g., with transmissions in neighboring or overlapping cells.Transmission power control signaling allows the mobile node to reduceand/or minimize transmission output power and thereby extend batterylife.

[0066] Timing control and timing control signaling module 324 is usedfor timing and timing signaling. Timing control is used in wirelessnetworking schemes such as, e.g., those with uplinks based on orthogonalfrequency division multiple access. To reduce the effects of noise, tonehopping may also be used. Tone hopping may be a function of time withdifferent mobile nodes being allocated different tones during differentsymbol transmission time periods, referred to as symbol times. In orderfor a base station 12 of a multiple access system to keep track of, anddistinguish between, signals from different mobile nodes, it isdesirable for the base station 12 to receive information from the mobilenodes in a synchronized manner. A drift of timing between the mobilenode 14 and the base station 12 can cause transmission interferencemaking it difficult for the base station to distinguish between symbolstransmitted by different mobile nodes, e.g., using the same tone, butduring different symbol time periods or using different tones but duringthe same symbol time period.

[0067] For example, the effect on a mobile node's distance from the basestation is a factor since transmissions from mobile node that arefarther from the base station 12 take longer to reach the base station12. A late arriving signal can interfere with another connection thathas hopped to the late arriving signal's frequency in a latter timeperiod. In order to maintain symbol timing synchronization, it isrequired to instruct a node to advance or delay its symbol transmissionstart time to take into consideration changes in signal propagation timeto the base station.

[0068] Data and data signaling module 328 is used to controltransmission and the reception of payload data, e.g., a channel or timeslot dedicated to the mobile node for signaling purposes. This includes,e.g., the data packets of an Internet file transfer operation.

[0069] In accordance with the present invention, the mobile node 14 canbe in one of four states. The signaling, power, and communicationsresources required by a mobile node will vary depending on the sate inwhich the mobile node is operating. As a result of using multiple statesin the mobile nodes, the base station 12 is able to allocate differentdegrees of communication resource, e.g., control and data signalingresource, to different mobile nodes as a function of the node's state ofoperation. This allows the base station 12 to support a greater numberof mobile nodes than would be possible if all nodes were continuously inthe on state. The particular state that the mobile node 14 is indetermines the control signaling and data signaling modules that areexecuted at any given time and also the level of control signalingbetween the mobile node and base station 12. The mobile node 14 can alsotake advantage of the different activity level in different states tosave power and extend battery life.

[0070] Operation of the mobile nodes 14 in different states, inaccordance with the present invention, will now be explained withreference to FIGS. 4 and 5. FIG. 4 illustrates a state diagram 400including four possible states, an access state 402, a on state 404, ahold state 410 and a sleep state 408, that a mobile node 14 can enter.Arrows are used in FIG. 4 to illustrate the possible transitions betweenthe four states.

[0071]FIG. 5 illustrates the mobile node modules 322, 324, 326, 328 thatare in the various states shown in FIG. 4. Each row of the chart 500corresponds to a different state. The first through fourth rows 502,504, 506, 508 correspond to the sleep state, access state, on state, andhold state, respectively. Each column of the chart 500 corresponds to adifferent module within the mobile node 14. For example, the firstcolumn 510 corresponds to the transmission power control and powercontrol signaling module 322, the second column 512 corresponds to thetiming control and timing control signaling module 324, the third column514 corresponds to the device status control and status signaling module326, while the last column 516 corresponds to the data and datasignaling module 328. In FIG. 5, solid lines are used to indicatemodules which are active in a particular state. Short dashed lines areused to indicate modules which may transition from an inactive orreduced activity level to a fully active status before the access stateis exited, assuming the modules are not already fully active. Longdashed lines are used to indicate a module which may be active in astate but which may perform signaling at a reduced rate while in theindicated state as opposed to the signaling rate implemented in the onstate.

[0072] From FIG. 5 it can be seen that during the sleep state the devicestatus control and status signaling module 326 remains active but theother modules are inactive allowing for power conservation and asignificantly restricting mobile node activity. In the access state 402,which serves as transition state, transmission power control and powercontrol signaling module 322, timing control and timing controlsignaling module 324 will become fully active (or active at a reducedrate in the case of the transmission power control and power controlsignaling module 322 in some embodiments) prior to leaving the accessstate 402 to enter the on-state 404 or hold state 410. In the on-state,all signaling modules 322, 324, 326, 328 are fully active requiring themost power from the mobile node's perspective and the highest allocationof communication resources, e.g., bandwidth, from the base station'sperspective. In the hold state, transmission power control and powercontrol signaling module 322 may be inactive or active at a much reducedsignaling rate. Timing control and timing control signaling module 324remains alive as does the device status control and status signalingmodule 326. The data and data signaling module 326 is either inactive oroperates to implement reduced functionality, e.g., receive data but nottransmit data as part of a communication session between various nodes.In this manner, the hold state allows bandwidth and other communicationsresources to be conserved while, in some cases, allowing the mobile nodeto receive, e.g., multi-cast signals and/or messages.

[0073] Each of the states, and potential transition between states, willnow be described in detail with reference to the state diagram of FIG.4.

[0074] Of the four states 402, 404, 410, 408, the on state 404 allowsthe mobile node to perform the widest range of supported communicationsactivities but requires the highest amount of signaling resources, e.g.,bandwidth. In this state 404, which may be thought of as a “fully-on”state, the mobile node 14 is allocated bandwidth on an as needed basisfor transmitting and receiving data, e.g., payload information such astext or video. The mobile node 14 is also allocated a dedicated uplinksignaling channel which it can use to make downlink channel qualityreports, communication resource requests, implement session signaling,etc. To be useful, these downlink channel quality reports should besignaled sufficiently frequently to track variations in the signalstrengths received by the mobile nodes.

[0075] During the on state 404, under control of module 324, the basestation 12 and mobile node 14 exchange timing control signals. Thisallows the mobile node 14 to periodically adjust its transmissiontiming, e.g., symbol timing, to take into consideration changes indistance and other factors which might cause the mobile node transmittedsignals to drift timing at the base station's receiver, with respect tothe signals transmitted by other mobile nodes 16. As discussed above,the use of symbol timing control signaling is employed in many systemswhich use orthogonal frequency division multiple access in the uplink,to avoid interference from transmission signals generated by multiplenodes in the same cell 10.

[0076] To provide transmission power control, during the on state 404,transmission power control signaling is employed, under direction ofmodule 322, to provide a feedback mechanism whereby a mobile node isable to efficiently control its transmission power levels based onsignals periodically received from the base station with which it iscommunicating. In this manner, a mobile node 14 can increase and/ordecrease its transmission power to provide for successful receipt ofsignals by the base station 12 without excessive wastage of power andtherefore reduced battery life. The power control signaling is carriedout sufficiently frequently to track variations in the signal strengthbetween the base station 12 and the mobile nodes 14, 16 for a certainminimum channel coherence time. The power control interval is a functionof channel coherence time. The power control signaling and the downlinkchannel quality reports are of similar time scale, and in general, occurat much higher rate than the timing control signaling required tosupport vehicular mobility.

[0077] From the on state 404, the mobile node 14 can transition intoeither the sleep state 408 or the hold state 410. Each of these statesrequires reduced communication resources, e.g., bandwidth, to supportthan does the on state 404. The transition may be in response to userinput, e.g., a user terminating a communications session or in responseto the loss of communications resources, e.g., bandwidth required tosupport the transmission and/or receipt of information to becommunicated such as voice or data information.

[0078] In accordance with the present invention, in the hold state, amobile node is denied bandwidth for transmitting payload data. However,timing control signaling is maintained and the mobile node is alsoallocated a dedicated uplink communication resource which it can use torequest changes to other states. This allows for instance a mobile nodeto obtain additional communications resources by requesting a transitionto on state where it could transmit payload data. Maintaining timingcontrol during the hold state 410 allows the mobile node 14 to transmitits uplink requests without generating interference to other mobiles 16within the same cell 10. Having a dedicated resource for transmittingrequests to the base station 12 also helps ensure that the delays forstate transition are minimal as these requests do not collide withsimilar requests from other mobiles.

[0079] From the hold state 410, the mobile node may transition into theon state 404, e.g., upon being granted a requested communicationresource. Alternatively, the mobile node can transition into the sleepstate 408. Since timing control signaling is maintained in the holdstate 410, when the mobile node transitions to the on state it cantransmit data without much delay, e.g., as soon as the requestedbandwidth is granted, without concerns about creating interference tothe uplink transmission of other mobile nodes in the cell which couldresult from a timing drift of the mobile node.

[0080] During the hold state 410, transmission power control signalingmay be discontinued or performed at greater intervals, e.g., at asimilar rate as timing control. In this manner, the resource, e.g., basestation to mobile node control resource, used for transmission powercontrol signaling can be eliminated or less resource can be dedicated tothis purpose than would be possible if power control signaling for allnodes 14, 16 in the hold state was performed at the same rate as in theon state. The mobile nodes 14, 16 transmission power control updates areperformed in the mobile node during the hold state at a reduced rate ornot at all, in a manner which corresponds to the reduced transmissionpower control signaling. When transitioning from the hold state 410 tothe on state 404, the mobile node 14 may start off with an initial highpower level to insure that its signals are received by the base station12. The power level is then reduced once transmission power controlsignaling resumes at a normal (full) rate as part of on state operation.

[0081] Transition from hold state can be initiated by base station or bythe mobile nodes. The base station may initiate a transition by sendinga page over a paging channel meant for the hold state users. In oneembodiment, the mobile decodes the paging channel with some prearrangedperiodicity, to check for base station messages. On finding a pagemessage meant for it, it responds with an acknowledgement. In variousembodiments the acknowledgement is transmitted over a shared resource onthe uplink and is slaved to the page or grant message on the downlink.The mobile node 14 responds to a state change message by moving to theassigned state specified in the received state change message.

[0082] In one embodiment, when the mobile node 14 intends to migratefrom the hold state 410 to the on state 404, it transmits a statetransition request using its dedicated uplink communications channel,which is not shared with any other mobile nodes 16. Since the channel isnot shared, the base station 12 is able to receive the request withoutinterference and promptly grant the request assuming the requiredresources are available taking into account the priority of the userand/or the applications that the user may be using. The mobile onreceiving a grant message meant for it, responds with anacknowledgement. The acknowledgment is transmitted over a sharedresource on the uplink and is slaved to the grant message on thedownlink.

[0083] In one exemplary embodiment, when the mobile node does not intendto migrate to another state from the hold state, the mobile node may nottransmit any signal in its dedicated uplink communication resource,though the dedicated resource has been assigned to the mobile node andtherefore will not be used by any other mobile nodes. In this case, themobile node can temporarily shut down the transmission module andrelated functions thereby conserving power.

[0084] In another embodiment, the mobile node uses an on/off signalingin its dedicated uplink communication resource, where the mobile nodesends a fixed signal (on) when it intends to migrate to another state ordoes not send any signal (off) when it does not intend to migrate to anyother state. In this case, the transmission of the fixed signal can beinterpreted as a migration request to the on state if the transmissionoccurs at certain time instances and as a migration request to the sleepstate if the transmission occurs at some other time instances.

[0085] In order to provide reachability for a large number of mobilenodes 14, 16, the sleep state 408, requiring relatively fewcommunications resources, is also supported. The mobile node 14 cantransition into the sleep state 408, e.g., in response to user input, aperiod of inactivity, or a signal from the base station 12, from any ofthe other supported states 404, 404, 410.

[0086] In the sleep state 408 the mobile node 14 may, at the behest ofthe base station 12, serving the cell 10 signal its presence in the cell10. However, little other signaling is supported during this state 408of operation. In the exemplary embodiment, during the sleep state 408,timing control signaling and power control signaling are not supported.In addition, the mobile node is not allocated a dedicated uplink formaking resource requests and is not allocated bandwidth for use intransmitting payload data, e.g., as part of a communications sessionwith another node 16 conducted through the base station 12.

[0087] Transitions from the sleep state 408 to another state 404, 410occur by passing through access state 402. A shared (contention based),as opposed to a dedicated uplink, communications channel is used tocontact the base station 12 to request resources necessary to transitionfrom the sleep state 408 to another state 402, 404, 410. Thesetransitions could be initiated by the base station on the paging channelor by the mobile nodes 14, 16. Since the communications channel used torequest resources to transition from the sleep state is shared, a mobilenode 14 may encounter delays before being able to successfully transmitthe resource request to the base station 12. This is due to possiblecollisions with similar requests from other mobile nodes. Such delaysare not encountered in regard to transitions from the hold state 410 tothe on state due to the use of a dedicated uplink resource for requestswhile in the hold state 410.

[0088] The access state 402 is a state through which a node 14 in thesleep state 408 can transition into one of the other supported states404, 410. The transition out of the sleep state is normally triggered,by an action by a user of the mobile node 14, e.g., an attempt totransmit data to another mobile node 16 or by the base station 12. Uponentering the access state 402, transmission power control and timingcontrol signaling has not yet been established. During access stateoperation, timing control signaling is established and, in variousembodiments, full or partial transmission power control signaling isestablished with mobile node transmission output power levels beingadjusted accordingly. A mobile node can transition from the access state402, back to the sleep state 408 or to either the on state 404 or thehold state 410. Transition to the sleep state 408 may occur, e.g., inresponse to a user canceling a transmission request or a base station 12denying the node the resources required to complete the transition tothe hold or on states 404, 410. Transition from the access state to theon state 404 or hold state 410 normally occurs once the mobile node 14has restored power and timing synchronization signaling with the basestation 12 and has been granted the communications resource or resourcesrequired to maintain the state into which the mobile node 14 istransitioning.

[0089] The establishment of the timing synchronization and transmissionpower control signaling, in the access state 402, can take some amountof time during which data transmission is delayed. Furthermore, as notedabove, delays may result form the use of a shared resources to requestthe transition which can produce contentions between mobile nodes whichtake time to resolve. In addition, because of the use of sharedresources in requesting a state transition, it is difficult toprioritize between different nodes requesting state transition.

[0090] In some embodiments, for an individual cell 10, the maximumnumber of mobile nodes 14, 16 that can be in the sleep state 408 at anygiven time is set to be greater than the maximum number of mobile nodes14, 16 that can be in the hold state 410 at given time. In addition, themaximum number of mobile nodes 14, 16 which can be in the hold state 410at any given time is set to be greater than the maximum number of nodesthat can be in the on state 404 at any given time.

[0091] By supporting a hold state in accordance with the presentinvention, in addition to a sleep state, such delays can be avoided fora number of mobile nodes 14, 16, as transition from the hold state 410to the on state 404 does not go through the access state, while thenumber of nodes which can be supported by a single base station 12 islarger than would be possible without the use of the reduced signalinghold state.

[0092] From a power standpoint it is desirable that the amount of timeand thus power a mobile node spends monitoring for control signals beminimized. In order to minimize the amount of time and power a mobilenode spends monitoring for control signals, at least some downlinkcontrol signaling, i.e., signaling from the base station to one or moremobile nodes, is performed using multiple control channels. In oneembodiment of the invention, particularly well suited for use withmobile nodes capable of supporting multiple states of operation, aplurality of control channels are provided for communicating controlsignals from the base station to the mobile nodes. Each of the pluralityof common control channels is divided into a number of segments, e.g.,time slots, where each segment is dedicated, e.g., assigned, for use byone or a group of mobile nodes. In this case, a group of mobile nodesmay be, e.g., a subset of the mobile nodes in the system whichcorrespond to a multicast message group. In such an embodiment, thecontrol channels are common to multiple nodes, but each segment of achannel is dedicated, e.g., corresponds to, a particular one of themobile nodes or group of mobile nodes with other mobile nodes beingexcluded from using the dedicated segments. The dedicated segments of acommon control channel corresponding to an individual mobile noderepresent a dedicated control channel allocated to the individual mobilenode.

[0093] The pattern of control channel segment allocation is made knownto the individual mobile nodes 14, 16 in a cell, e.g., based oninformation transmitted to each particular node 14, 16 from the basestation 12.

[0094] To provide particularly efficient control channel signaling, basestation to mobile node control signaling may be performed at severaldifferent rates, with a different control channel being used for each ofthe different control channel signaling rates.

[0095] In order to minimize the amount of power and resources consumedby the task of monitoring control channels for information relevant to amobile node, each mobile node need only monitor to detect signals incontrol channel segments assigned to the particular node. This allowsthe mobile nodes to schedule control channel monitoring operations sothat the control channels need not be monitored on a continuous basiswhile still allowing the mobile nodes to receive control signals in atimely manner.

[0096] In one embodiment which is particularly well suited for use wheremobile nodes that support at least an on state, a hold state and a sleepstate, three different segmented control channels are used. The threecontrol channels include an assignment control channel, a fast pagingcontrol channel, and a slow paging control channel.

[0097] The fast paging control channel and slow paging control channelare periodic in nature, e.g., control signals are not transmitted interms of time on a continuous basis in these channels. Thus, mobilenodes need not spend power and resources monitoring these channels on acontinuous basis. In some embodiments, to further reduce the amount oftime and power a mobile needs to spend monitoring the fast and slowpaging channels, the channels are segmented and the segments arededicated to particular mobile nodes or groups of mobile nodes.

[0098] In order to minimize the amount of power and resources consumedby the task of monitoring control channels for information relevant to amobile node, each mobile node need only monitor to detect signals in thefast and slow paging control channel segments assigned to the particularnode. This allows the mobile nodes to schedule control channelmonitoring operations so that the control channels can be monitored on aless frequent basis than would be possible if all segments need to bemonitored for control signals.

[0099]FIG. 6 illustrates control signals 602, 620, 630 corresponding toexemplary assignment, fast paging and slow paging downlink controlchannels respectively. The fast paging control channel signal 602 isdivided into a plurality of segments, e.g., 1 ms time slots.Transmission in the assignment channel occurs, in the FIG. 6 embodiment,on a continuous basis. For each time slot, there is a correspondingtraffic channel segment or segments. Traffic channel segments areallocated by the base station 12 to mobile nodes 14, 16 by transmittinga mobile node identifier or mobile node group identifier in a time slotto indicate that the corresponding traffic segment or segments have beenassigned for use to the mobile node(s) corresponding to the transmittedidentifier. While in the on state mobile nodes 14, 16 monitor theassignment channel on a continuous basis, e.g., at a rate sufficient todetect the identifier included in each segment of the control channelused for traffic assignment purposes.

[0100] During the on state, in addition to the assignment channel eachmobile node 14, 16 monitors the periodic fast paging and slow pagingchannels.

[0101] In FIG. 6, fast paging signal 620 can be seen to be periodic innature. Each exemplary fast paging signal period 622, 626, 230, 634 is10 ms in duration. However, of this 10 ms period, the fast paging signalis actually transmitted for only a fraction of the full period, e.g., 2ms. The periods 623, 627, 631, 635 in which the fast paging signal istransmitted are segmented into time slots. The remaining portions 624,628, 632, 636 represent portions of time in which the fast pagingcontrol signal is not broadcast by the base station 12. While only two 1ms segments are shown in each fast paging on period 623, 627, 631, 635it is to be understood that there are normally several segments per onperiod.

[0102] To reduce the amount of time mobile nodes 14, 16 need monitor forfast paging control signals, fast paging control channel segments are,in some embodiments, dedicated to individual mobile nodes or groups ofmobile nodes. The information on which segments are dedicated to whichmobile nodes is normally conveyed to the mobile nodes 14, 16, e.g., formthe base station 12. Once the dedication information is known, themobile nodes 14, 16 can limit their monitoring of fast paging channelsegments to segments which are dedicated to them. In such embodiments,mobile nodes can monitor the fast paging channel at periodic intervalsgreater than the fast paging period without risking missing controlinformation transmitted to the mobile on the fast paging channel.

[0103] The segments of the fast paging channel are used to conveyinformation, e.g., commands, used to control the mobile node totransition between states. The segments of the fast paging channel canalso be used to instruct the mobile node to monitor the assignmentchannel, e.g., when the mobile node is in a state which has caused it tostop monitoring the assignment channel. Since the mobile nodes of thesystem know which segments of the fast paging channel are assigned tothem, commands may be included in the fast paging channel segmentswithout mobile node identifiers making for an efficient transmissionscheme.

[0104] The slow paging channel is segmented and used to conveyinformation in the same manner as the fast paging channel. Theinformation conveyed using the slow paging channel may be the same as,or similar to, the information and commands that are transmitted usingthe fast paging channel.

[0105] In FIG. 6, signal 630 represents an exemplary slow paging channelsignal. Note that the full slow paging signal period 632 is longer thanthe paging period 622 of the fast paging channel. Reference numbers 631and 634 are used in FIG. 6 to show portions of a slow paging period.Given that the slow paging period is longer than the fast paging period,the time between control signal transmission in the slow paging channeltends to be greater than in the fast paging channel. This means that themobile node may discontinue monitoring the slow paging channel forlonger intervals than is possible with the fast paging channel. It alsoimplies, however, that it may take, on average, longer for a controlsignal transmitted on the slow paging channel to be received by theintended mobile node.

[0106] In FIG. 6, two slow paging signal transmission on signal periods640, 642 are shown. Signal periods 639, 641, 643 correspond to slowpaging channel signal periods during which no slow paging signal istransmitted.

[0107] Since the fast and slow paging channels are period in nature, ifthe transmission on periods are staggered so that they do not overlap,the fast and slow paging channels may be implemented using the samephysical transmission resources, e.g., tones, with the tones beinginterpreted as corresponding to either the fast or slow paging channeldepending on the time period to which the tones correspond.

[0108] The spacing between segments allocated to a particular mobilenode in the slow paging channel are often, but need not be, greater thanin the fast paging channel. This generally means, in terms of time, thata mobile device needs to monitor the slow paging channel at intervalswhich are more widely spaced than the intervals at which the fast pagingchannel is monitored. As a result of the greater spacing of the segmentsin the slow paging channel, power required to monitor this channel isnormally less than that required to monitor the fast paging channel.

[0109] In accordance with one embodiment of the present inventiondifferent numbers of downlink control channels are monitored indifferent states. In such embodiments, the assignment, fast paging andslow paging channels are not monitored in all states. Rather, in the onstate the greatest number of downlink control channels are monitored,fewer downlink control channels are monitored in the hold state and thelowest number of downlink control channels are monitored in the sleepstate.

[0110]FIG. 7 shows a table 700 which illustrates the three exemplarybase station to mobile node (downlink) control signaling channels andthe corresponding four exemplary mobile node states of operationdiscussed above. In the table 700, a check is used to show controlchannels which are monitored for a given state while an X is used toindicate a control channel which is not monitored. A dashed check isused to show a control channel which may not be monitored during aportion of the time in that state but is monitored for at least aportion of the time in the state.

[0111] From FIG. 7 the first row 702 corresponds to the on state, thesecond row 704 corresponds to the access state, the third row 706corresponds to the hold state and the fourth row 708 corresponds to thesleep state. Columns in the table 700 correspond to different segmentedcontrol channels. The first column 710 corresponds to the assignmentchannel, the second column 712 corresponds to the fast paging channel,while the third column 714 corresponds to the slow paging channel.

[0112] As can be seen from the table 700, while in the on state a mobilenode 14, 16 monitors the assignment channel, fast paging control channeland slow paging control channel. For a portion of the access state,which represents a transition between the on state and either the holdstate or the sleep state, the assignment and fast paging channels aremonitored. The slow paging channel is monitored for the full period oftime the mobile node remains in the access state. As discussed above,monitoring of the fast paging and slow paging channels requires a mobilenode to be actively engaged in monitoring on a periodic, as opposed to acontinuous, basis.

[0113] While in the hold state, the assignment channel is not monitored.However, the fast paging channel and slow paging channel are monitored.Accordingly, a mobile node in the hold state can be instructed to changestates and/or monitor the assignment channel for traffic channel segmentassignment information in a relatively short period of time.

[0114] In the sleep state, of the three control channels shown in FIG.6, only the slow paging channel is monitored by the mobile node.Accordingly, a mobile node 14, 16 in the hold state can be instructed tochange states and/or monitor the assignment channel for traffic channelsegment assignment information but such instructions may take longer tobe detected, on average, than when in the hold state.

[0115] By decreasing the number of control channels that are monitoredas operation proceeds from the on state to the less active sleep state,mobile node monitoring and processing resources, and thus powerconsumption, can be effectively controlled. Thus, the sleep staterequires less mobile node resources, including power, than the holdstate. Similarly, the hold state requires less mobile node resources,including power, than the on state.

[0116] Mobile node transitions from active to less active states ofoperation may occur in response to commands to change states receivedfrom a base station. However, in various embodiments of the inventionsuch transitions are also initiated by mobile nodes 14, 16 in responseto detecting periods of downlink control signal inactivity or reducedactivity pertaining to the mobile node.

[0117] In one embodiment of the invention, activity relating to a mobilenode 14, 16 on the control channel which will cease to be monitored ifthe mobile node reduces its state of activity by one level is used todetermine when the mobile node should, on its own, switch to the loweractivity level state of operation. For example, in the case of the onstate, a mobile node monitors the assignment channel for signalsdirected to it. When failing to detect signals on the assignment channelfor a preselected period of time, or a reduced message level for aperiod of time, the mobile node 14, 16 switches from the on state to thehold state and ceases to monitor the assignment channel.

[0118] While in the hold state, the mobile node 14, 16 monitors the fastpaging channel for activity to determine, among other things, if itshould switch to a lower activity state of operation, e.g., the sleepstate. When failing to detect signals for a preselected period of time,or a reduced signal level for a period of time, the mobile node 14, 16switches from the hold state to the sleep state and ceases to monitorthe fast paging channel.

[0119] The wireless terminal can be controlled to operate at differenttimes in different operational states including an on state, a holdstate, and a sleep state. Table 800 of FIG. 8 illustrates the controloperations and signaling within the wireless terminals for each of thethree states, on, hold, and sleep in a particular exemplary embodiment.First row 802 corresponds to the on state; second row 804 corresponds tothe hold state; third row 806 corresponds to the sleep state. Eachcolumn of Table 800 refers to a module in the wireless terminal. Firstcolumn 810 corresponds to the transmission power control and powercontrol signaling module 322; second column 812 refers to timing controland timing control signaling module 324; third column 814 corresponds todevice status control and status signaling module 326; fourth column 816corresponds to data and data signaling module 328.

[0120] Operation of the transmission power control and power controlsignaling module 322 may include generating and processing power controlinformation, communicating, e.g. transmitting and receiving, powercontrol signaling between the wireless terminal and a base station.Operation of the timing control and timing control signaling module 324may include generating and processing timing control information,communicating, e.g. transmitting and receiving, timing control signalingbetween the wireless terminal and a base station. Operation of thedevice status control and status signaling module 326 may includegenerating and processing status control information such as state, anduplink requests for change of state or requests for more resources.Operation of the data and data signaling module 328 may includegenerating and processing data, e.g., user data, processing uplink anddownlink assignment information, e.g., uplink assignments or grants touser requests and communicating, e.g. transmitting and/or receiving userdata and uplink/downlink assignment information.

[0121] If the module is used, in accordance with the invention, duringthe state, it is shown with a solid line border in the row correspondingto the state. If the module is optionally used in some embodiments ofthe invention, and not used in other embodiments, the module is shown aswith a dashed line border in the row corresponding to the state. If themodule is not used in the given state, it is not shown in the rowcorresponding to that state. In the on state, transmission power controland power signaling module 322, timing control and timing controlsignaling module 324, device status and control and status signalingmodule 326, and data and data signaling module 328 are used. In the holdstate, modules 322, 324, 326, and 328 are used. In the hold state,transmission power control and power control signaling module 322 isoptionally used in some embodiments. However, in the hold state, thedata and data signaling mode the module 328 operates on received datafrom the base station and cannot send uplink data to the base station.In the sleep state, device status control and status signaling module326 is used and transmission power control and power control signalingmodule 322 is optionally used in some embodiments.

[0122] Transition between states may be initiated in response to achange in user activity including entry of user input through a wirelessterminal input device. When a wireless terminal is operated in a sleepstate or a hold state, there may be, in some embodiments, a period of 10msec or longer during which the wireless terminal does not transmitsignals. This is in contrast to some known systems which require signalsperiodically, e.g., at intervals of about 1 ms even in low power modesof operation. In some embodiments, the base station controls thetransition between states of a wireless terminal within its cell as afunction of one or more various profiles associated with the wirelessterminal such as Quality of Service profile and traffic Quality ofservice profile. In other embodiments, the wireless terminal controlsits transitions between states as a function of one or more variousprofiles associated with the wireless terminal such as Quality ofService profile and/or traffic Quality of service profile. Such Qualityprofiles may, and in various embodiments are, stored in the base stationand/or wireless terminal.

[0123] Operating the wireless terminal in different states requiresdifferent levels of communication resources, e.g., communicationsbandwidth, including channels which include communication channelsegments used by the wireless terminal. Communication channel segmentsare typically allocated by the base station to wireless terminals andmay be allocated as a dedicated segment, e.g., assigned to one wirelessterminal, or as a shared or common segment, e.g., assigned or madeavailable to a plurality of wireless terminals. In some embodiments,operating the wireless terminal in the on state uses the most controlsignaling resources, operating in the hold state uses a subset of the onstate control signal resources, and operating in the sleep staterequires a subset of the hold state control signaling resources. Suchcommunications resources, e.g., control channel resources, may includeuplink and downlink control signaling channel segments.

[0124] Each channel includes a plurality of transmission segments whichcan be used to transmit signal. Each segment may correspond to one ormore units of communication bandwidth, e.g., where communicationbandwidth may be 1 tone for a particular time period such as a symboltime. Channels may include uplink data channels, downlink data channels,uplink assignment channels, downlink assignment channels, uplink powercontrol information signaling channels, downlink power control signalingchannels, uplink timing control signaling channels, downlink timingcontrol signaling channels, dedicated uplink request channels, andcommon uplink request channels. Control signaling on the downlink may beby transmitting messages, e.g., on a paging channel, which are monitoredby one or more wireless terminals.

[0125] In one embodiment channel segments for a wireless terminal areallocated from various channels during various states as follows:

[0126] sleep state—common uplink request channel;

[0127] hold state—common uplink request channel, dedicated uplinkrequest channel (primary choice for uplink requests), downlinkassignment channel, downlink data channel, uplink power control channel(low rate), downlink power control channels (low rate), uplink timingcontrol channel (low rate), downlink timing control channel (low rate);

[0128] on state—common uplink request channel, dedicated uplink requestchannel, downlink assignment channel, downlink data channel, uplinkpower control channel (high rate), downlink power control channel (highrate), uplink timing control channel (high rate), downlink timingcontrol channel (high rate), uplink assignment channel, uplink datachannel.

[0129] Graph 902 shows an exemplary uplink data channel 904 on thevertical axis and time, represented by n segments, 906 on the horizontalaxis. Graph 902 also shows an exemplary uplink channel segment 908 thatmay be used for transmitting uplink data signals including user datafrom a wireless terminal to a base station. When the wireless terminalis in the on state, wireless terminals may be assigned uplink datachannel segments and uplink data signaling may occur. Data and datasignaling module 328 is active in the wireless terminal during thisoperation. In the hold state, the base station allocates zero uplinkdata channel segments 908, e.g., zero user data uplink resources to thewireless terminal.

[0130] Graph 912 shows an exemplary downlink data channel 914 on thevertical axis and time, represented by n segments, 916 on the horizontalaxis. Graph 912 also shows an exemplary downlink data channel segment918 that may be used for transmitting downlink data signaling, includingdata from a base station to one or a plurality of wireless terminals. Ifthe wireless terminals are in either the On state or the Hold state,data and data signaling modules 328 may receive and process downlinkdata signaling in the downlink data channel segment 918. Multipleterminals, e.g., terminals corresponding to a broadcast group, maymonitor the data channel at the same time in various embodiments such asin the case where multiple wireless terminals are members of the samebroadcast group.

[0131] User data in downlink data channel segments 918 may include textinformation addressed to a group and wireless terminals may monitor forthe group address to which the wireless terminal belongs. Hold stateoperation of a wireless terminal may also include receiving sharedinformation, e.g. broadcast information addressed to a group in downlinksegments 918. In some embodiments, in the hold state, various downlinksignaling other than power control and timing control signaling may besent by the base station in exemplary downlink channel segments 918 andmonitored by the wireless terminals. In some embodiments, in the holdstate, power control and timing control signaling may be restricted tobe less than the on-state or not performed at all. In the hold state,the base station may select to reduce data signaling to wirelessterminals and in such a case the base station may not transmit signalingin a downlink assignment channel segment to any wireless terminal duringa downlink assignment signaling transition period. The data channelsegment corresponding to an unused downlink assignment segment will gounused in such a case. In some embodiments, in a cell, the base stationis operated to allocate over at least one one second time period moredownlink data channel segments 918, e.g. used to communicate user data,to wireless terminals in the on state than to wireless terminals in thehold state. The user data may exclude timing and power control signals.In some embodiments, 75% of the downlink data channel signaling segments918 during at least one one second time period are dedicated to wirelessterminals in the on state. In other embodiments, 90% of the downlinkdata channel signaling segments 918 during at least one one second timeperiod are dedicated to wireless terminals in the on state. In someembodiments, in the hold state, the base station allocates a portion ofthe downlink signaling resources to communicate data or information forpurposes other than data downlink assignments and/or user data downlinktransmissions.

[0132] Graph 942 shows an exemplary uplink power control signalingchannel 944 on the vertical axis and time, represented by n segments,946 on the horizontal axis. Graph 942 also shows exemplary uplink powercontrol channel segments 948 and 950 that may be used for transmittingpower control signaling, e.g. power control information, from a wirelessterminal to a base station. The power control module 322 in the wirelessterminal may be active in the on state, hold state, or, in someembodiments, the sleep state. This allows power control signaling tooccur in each of these states, e.g., using uplink power control channelsegments 948 and 950. Transmission power control and power controlsignaling module 322 is active in the wireless terminal during powercontrol signal generation, transmission and reception operations.

[0133] Graph 962 shows an exemplary downlink power control signalingchannel 964 on the vertical axis and time, represented by n segments,966 on the horizontal axis. Graph 962 also shows exemplary downlinkpower control channel segments 968 and 970 that may be used fortransmitting power control signaling, including power controlinformation from a base station to a wireless terminal. The powercontrol module 322 in the wireless terminal may be active in the onstate, hold state, or, in some embodiments, sleep state. This allowsdownlink power control signaling to occur on the downlink power controlchannel segments 968 and 970. If transmission power control and powercontrol signaling module 322 is active in the wireless terminal, thewireless terminal may receive and processes power control signalingduring this operation.

[0134] In various embodiments, various power control signaling rates mayapply in different states. In an exemplary case, assume that uplinkpower control signaling occurs in uplink power control signaling channelsegments 948, 950 and that downlink power control signaling occurs indownlink power control signaling channel segments 968, 970. The timeintervals between exemplary uplink power control signaling in segments948, 950 may be used to define an uplink power control signaling rate,e.g., a wireless terminal transmitted power control signaling rate. Thetime intervals between exemplary downlink power control signaling insegments 968 and 970 may be used to define a downlink power controlsignaling rate, e.g., a base station power control signaling rate withrespect to one wireless terminal. The ensemble, e.g., combination, ofthe power control signaling in both uplink and downlink channel segments948, 950, 968, 970 over a given time represents the power controlsignaling rate since both uplink and downlink power control signals arepart of the power control signaling process.

[0135] Power Control information may be communicated between the basestation and the wireless terminal as previously discussed. With respectto the rate of communicating power control information between the basestation and the wireless terminal, in some embodiments, the signalingrate is greater in the on state than in the hold state, and thesignaling rate is higher in the in the hold state than in the sleepstate. In some embodiments the signaling rate of communicating the powercontrol information in the sleep state is 0, i.e. there is no powercontrol information transfer in sleep state between the base station andthe wireless terminal in some embodiments. In some embodiment, the powercontrol information signaling rate in the on state is at least twice therate in hold state. In some embodiments, the power control informationsignaling rate in the on state is at least twice the rate in hold state,and the rate in sleep state is less than the rate in hold state. In someembodiments, in the hold state, the power control signaling occurs atintervals at least 10 msec apart. In some embodiments, the rate ofcommunicated power control information is controlled with respect to theon state and the sleep state, such that, the rate in the on state isgreater than the rate in the sleep state. In still other embodimentspower control and/or timing is not performed in the hold state or isperformed at a rate lower than in the on state. Power control signalingand/or timing control signaling are not performed, in variousembodiments, in the sleep state. Timing control may be performed in saidsleep state at a lower rate than in said hold state.

[0136] Graph 972 shows an exemplary uplink timing control signalingchannel 974 on the vertical axis and time, represented by n segments,976 on the horizontal axis. Graph 972 also shows exemplary uplink timingcontrol signaling channel segments 978 and 980 that may include uplinktiming control signaling, including timing control information such as,e.g., clock synchronization information, from a wireless terminal to abase station. The wireless terminal may be in the on state or hold statewhen uplink timing control signaling occurs in uplink timing controlsignaling segments 978, 980. Timing control and timing control signalingmodule 324 is active in the wireless terminal during this operation,e.g., during the generation, receipt and/or processing of timing controlsignals.

[0137] Graph 982 shows an exemplary downlink timing control signalingchannel 984 on the vertical axis and time, represented by n segments,986 on the horizontal axis. Graph 982 also shows exemplary downlinktiming control signaling channel segments 988 and 990 that may includedownlink timing control signaling, including timing control informationfrom a base station to a wireless terminal. The wireless terminal may bein the on state or hold state in order to be able to receive and processdownlink timing control signaling in segments 988 and 990 when suchsignaling occurs. Timing control and timing control signaling module 324is active in the wireless terminal when receiving and processing thesignaling during this operation. Exemplary downlink timing controlsignaling segments 988 and 990 are dedicated segments by a base stationto a specific wireless terminal to the exclusion of other wirelessterminals in one embodiment.

[0138] In various embodiments, various timing control signaling ratesmay apply. In an exemplary case, assume that uplink timing controlsignaling occurs in uplink timing control signaling channel segments978, 980 and that downlink timing control signaling occurs in downlinktiming control signaling channel segments 988, 990. The time intervalsbetween exemplary uplink timing control signaling in segments 978, 980may be used to define an uplink timing control signaling rate, e.g., arate at which timing control signals are generated by a wirelessterminal. The time intervals between exemplary downlink timing controlsignaling in segments 988 and 990 may be used to define a downlinkcontrol signaling rate, e.g. a base station timing control signalingrate with respect to one wireless terminal. The combination of thetiming control signaling in both uplink and downlink channel segments978, 980, 988, 990 over a given time may be used in various embodimentsto define a timing control signaling rate.

[0139] The invention supports, in various embodiments, timing controlsignaling between the base station and the wireless terminal in the onstate and the hold state as previously described. In some embodiments,timing control is not performed in the hold state. In some embodiments,the rate of timing control signaling between the base station and thewireless terminal is greater than or equal to the timing controlsignaling rate in the hold state. In some embodiments, while in the onstate, the power control information signaling rate, e.g., the wirelessterminal transmitted power control signaling rate, is greater than orequal to the timing control signaling rate, e.g., the wireless terminaltransmitted timing control signaling rate. In other embodiments, whilein either the on state or the hold state, the power control signalingrate is greater than or equal to the timing control signaling rate.

[0140] In some embodiments, in the hold state, the wireless terminaldoes not receive any downlink dedicated communications resources, e.g.,channel segments, other than the power control signaling channelsegments 948, 950, 968, 970 and the timing control signaling channelsegments 978, 980, 988, 990. In such an embodiment, in the hold state, awireless terminal only receives downlink control signaling from thedownlink resource that is shared by multiple wireless terminals, e.g.,monitored by multiple wireless terminals. In such an embodiment, in thehold state, a wireless terminal does not receive downlink controlsignaling from any downlink resource that is dedicated to the wirelessterminal.

[0141] In some embodiments, in the sleep state, zero downlink resourcesare dedicated to wireless terminals. In some embodiments, the timingcontrol signaling, e.g. signaling in uplink segment 978, 980, and/orsignaling in downlink segment 988 and 990 includes timing controlmessages which may be transmitted at non-regular time intervals.

[0142] In some embodiments the timing control signals are messages thatmay be transmitted at previously undetermined times. In someembodiments, the timing control resources are dedicated communicationsresources that have been assigned to a specific wireless terminal.

[0143] Graph 992 shows an exemplary dedicated uplink request signalingchannel 994 on the vertical axis and time, represented by n segments,996 on the horizontal axis. Graph 992 also shows an exemplary dedicateduplink request signaling channel segment 998 which may include uplinkrequest signaling, including an uplink request from a wireless terminalto a base station. The uplink request may also be referred to as apaging request from the wireless terminal to the base station. Thewireless terminal may, in some embodiments, be in the on state, holdstate, or sleep state when an uplink request signaling occurs in uplinkrequest signaling channel segment 998. In other embodiments, thewireless terminal is not allocated dedicated uplink request channelsegments in the sleep state. The uplink request signaling in segment 998may be, e.g., a request to change, e.g., from hold state to on or sleepstate. The uplink request signaling in segment 998 may also be a requestfor increased bandwidth, which may be interpreted by the base station asa request to change state. Device status and status signaling module 326is active in the wireless terminal during this operation. Uplink Requestsignaling channel 994 is a dedicated channel, so that the wirelessterminal is assigned a dedicated channel segment 998 and will not havecontention problems or associated delays when attempting to reach thebase station. In some embodiments wireless terminals are assigneddedicated uplink request channel segments in the hold or on state. Insome embodiments, during the hold state, a wireless terminal maytransmit at most a small number of bits over dedicated uplink requestsignaling channel 994 during any one uplink signaling transmissionperiod, e.g. segment 998. In one embodiment, during the hold state, awireless terminal may transmit at most 8 bits over dedicated uplinkrequest signaling channel 994 during any one uplink signalingtransmission period, e.g. segment 998. In the hold state of operation,in some embodiments, the wireless terminal is allowed to let at leastone dedicated uplink channel segment 998 to go unused, i.e., thewireless terminal does not transmit any signal into a dedicated uplinkchannel segment 998.

[0144] In some embodiments, operation in the hold state includes adedicated uplink communications resource, e.g. segments 948, 950, 968,970, 998, to transmit information in addition to power control andtiming control information to the base station; this additionalinformation may include state transition request and/or requests foradditional bandwidth. In some embodiments, use of this hold statededicated uplink resource e.g. segments 948, 950, 968, 970, 998 may berestricted to power control information, timing control information, andtransition state request. In some embodiments, the Hold state dedicateduplink resource includes transmission segments, e.g., one or moresegments from any of the segments 948, 950, 968, 970, 978, dedicated tothe wireless terminal, some of which are allowed to go unused. In someembodiments, during hold state, state transitions requests arecontention free due to the use of uplink communication resource segments998 dedicated to the wireless terminal for transmission of statetransition requests.

[0145] Graph 1002 shows an exemplary common uplink request signalingchannel 1004 on the vertical axis and time, represented by n segments,1006 on the horizontal axis. Graph 1002 also shows an exemplary commonuplink request signaling segment 1006 that may include an uplink requestfrom a wireless terminal to a base station. The uplink request signalmay be referred to as a paging request signal from the wireless terminalto the base station. The wireless terminal may be in the on state, holdstate, or sleep state when uplink request signaling occurs in the commonuplink request channel segment 1006. The uplink request signaling insegment 1006 may be a request to change state. The uplink requestsignaling in segment 1006 may be a request for more bandwidth which maybe interpreted by the base station as a request to change state, e.g.,from sleep state to hold state. Device status and status signalingmodule 326 is active in the wireless terminal during this operation.Uplink Request signaling channel segment 1006 is a common or contentionbased channel segment; therefore, multiple wireless terminals mayattempt or contend for the channel segment to transmit requests to thebase station. If request attempts from multiple wireless terminals occurat the same time, collisions or interference between two wirelessterminals requests signals may occur resulting in the wireless terminalhaving to retransmit the request attempt to the base station. In someembodiments of the invention, in the sleep mode, common uplink requestchannel segments 1006 are available to wireless terminals, but dedicateduplink request channel segments 998 are unavailable. In one embodiment,the wireless terminal, while in the sleep state, uses the common uplinkrequest signaling segment 1006 to transmit a state change request signalto the base station, requesting a transition from sleep state to hold oron state. The transmission of an uplink channel resource request insegment 1006 may be performed as part of a transition from sleep stateto hold or on state.

[0146] In some embodiments, in the hold state of operation, the wirelessterminal has no dedicated downlink signaling resources, e.g., nodedicated downlink signaling channel segments. In such an embodiment,the base station, decides when to transmit downlink data on downlinkdata channel signaling segment 718.

[0147] Graph 922 shows an exemplary uplink assignment signaling channel924 on the vertical axis and time, represented by n segments, 926 on thehorizontal axis. The uplink assignment channel 924 may also be referredto as a paging notification channel. Graph 922 also shows exemplaryuplink assignment channel signaling segments 928, 930 which may includeuplink assignment signaling including information relating to theallocation of uplink resources for the communication of data from awireless terminal to a base station, e.g. allocation of uplink datachannel signaling segments 908 to the wireless terminal. The uplinkassignment channel signaling in segments 928, 930 is periodicallybroadcast signaling from the base station to the wireless terminals. Thesignaling may include a notification to a wireless terminal, if itsrequest signaling, for e.g. more bandwidth or state change, in uplinkrequest channel segments 998 or 1006, has been granted by the basestation. Assuming that the wireless terminal was in hold state, andrequest for more bandwidth has been granted, an ID for the wirelessterminal is included in the uplink assignment channel segment, e.g.,segment 928. There is a known preselected relationship between thenotification signaling in the assignment channel, e.g., segment 928, andthe allocation of an uplink data channel segment 908 to the wirelessterminal for use by the wireless terminal to transmit data andinformation to the base station. In order for the wireless terminal toreceive and processes uplink allocation signaling in segments 928,device status control and status signaling module 326 is active in thewireless terminal. In another example, the wireless terminal may also bein the on state and send a signaling request for increased uplink databandwidth, to send more data to the base station, resulting in grantedallocation signaling in uplink assignment segment 928.

[0148] In some embodiments, the interval between the request forresources and grant of resources may be a function of the state thewireless terminal is in or a function of whether the request signalingcame over a dedicated segment 998 or a common segment 1006.

[0149] Graph 932 shows an exemplary downlink assignment channel 934 onthe vertical axis and time, represented by n segments, 936 on thehorizontal axis. Graph 932 also shows exemplary downlink assignmentchannel signaling segments 938 and 940 that may include downlinkassignment signaling from a base station to one or a plurality ofwireless terminal. The base station may periodically broadcast downlinkassignment information including ID for specific wireless terminals. TheID may be an ID for a specific wireless terminal or may be a group IDapplying to a group of wireless terminals. The wireless terminals maylisten to the downlink assignment signaling in segments 938 and 940 andlook for their ID. The wireless terminal may be in the on state or holdstate to receive and process the downlink assignment signalinginformation in segments 938, 940. Data and data signaling modulesignaling module 328 is active in the wireless terminal and processesthe received signaling during this operation. If a wireless terminalrecognizes its ID in the signaling in the downlink assignment channelsegment, e.g. segment 938, it knows to look for base station downlinkdata channel segments 918. There is a known preselecteed relationshipbetween the notification signaling in the downlink assignment channelsegment 938 and the transmission of the corresponding data in thedownlink data channel segment 918, allowing the wireless terminal ifmonitoring to receive and process the corresponding data transmission inthe downlink channel segment 918 which has been assigned via thenotification signaling.

[0150] In some embodiments, the base station may allow at least somesegment 938, 940 of downlink assignment channel 934 to go unused, e.g.the base station does not transmit any signals into some of the downlinkassignment signaling segments 938, 940.

[0151] In the hold state, the wireless terminal may receive downlinksignaling in segments 938, 940 other than timing control or powercontrol information. The signaling in segments 938, 940 may be monitoredby multiple wireless terminals for information.

[0152] Using the above discussed methods, monitoring, signal processingand power resources can be conserved in a mobile node 14, 16 through theuse of multiple states of operation and through the use of multiplesegmented control channels. In addition, limited control resources,e.g., bandwidth used for communicating control information from a basestation to a mobile node, is used efficiently as a result of usingmultiple control channels, e.g., segmented control channels of the typedescribed above.

[0153] Numerous variations on the above described methods and apparatuswill be apparent to one of ordinary skill in the art in view of theabove description of the invention. Such variations remain within thescope of the invention.

What is claimed is:
 1. A communications method, the method comprising:operating a wireless terminal, at different times, in each one of atleast three different operational states, the three differentoperational states including an first state, a second state and a thirdstate, wherein operating the wireless terminal in the first stateincludes using a first amount of a control communications resource usedto send control signals between a base station and said wirelessterminal; wherein operating the wireless terminal in the second stateincludes using a second amount of said control communications resource,said second amount of said control communications resource being lessthan said first amount, said used second amount of said controlcommunications resource including a dedicated uplink signaling channeland a shared downlink signaling channel used to communicate informationrelating to the allocation of uplink and downlink resources for thecommunication of data, respectively; and wherein operating the wirelessterminal in the third state includes using a third amount of saidcontrol communications resource which is less than said first and secondamounts.
 2. The method of claim 1, wherein transitioning from one ofsaid three states to another one of said three states in response to achange in user activity.
 3. The method of claim 1, wherein said firststate is an on state, said second state is a hold state, and said thirdstate is a sleep state.
 4. The method of claim 1, wherein said thirdamount of control communications resource includes a third set ofcommunications elements, which said second amount of controlcommunications resource includes a second set of communications elementswhich includes additional communications elements in addition to saidthird set of communications elements, and where said first amount ofcontrol communications resource includes a first set of communicationselements which includes said second set of communications elements inaddition to said second set of communications elements.
 5. The method ofclaim 4, wherein said communications elements correspond to segments ofcommunications channels used by said wireless terminal.
 6. The method ofclaim 1, wherein operating in said second state includes: transmittingat most, a small number of bits over said uplink signaling channelduring any one uplink signaling transmission period.
 7. The method ofclaim 6, wherein said small number of bits includes at most 8 bits. 8.The method of claim 1, wherein operating said wireless terminal in saidsecond state includes allowing at least one uplink channel segmentdedicated to use by said wireless terminal to go unused, said wirelessterminal not transmitting any signal into said dedicated uplink channelsegment.
 9. The method of claim 1, wherein operating said wirelessterminal in said second state includes transmitting a state transitionrequest using an uplink channel segment dedicated to said wirelessterminal, the dedication of said uplink channel segment to said wirelessterminal avoiding possible contention with other wireless terminals foruse of said dedicated uplink channel segment.
 10. The method of claim 1,wherein in said second state said wireless terminal does not receive anydownlink control resources dedicated exclusively to said wirelessterminal other than downlink resources used for power control or timingcontrol signaling.
 11. The method of claim 1, further comprisingoperating a base station to communicate with a plurality of wirelessterminals, said wireless terminal being one of said plurality ofwireless terminals, operating said base station including allowing atleast some segments of a downlink allocation assignment channel to gounused, said base station not transmitting anything into said unuseddownlink allocation assignment channel segments.
 12. The method of claim1, wherein operating said wireless terminal in said third stateincludes: transmitting an uplink channel resource allocation request ina segment of a common signaling channel into which other wirelessterminals can also transmit uplink channel resource allocation requeststhereby possibly creating signaling conflicts.
 13. The method of claim12, wherein said step of transmitting an uplink channel resourceallocation request is performed as part of a transition from said thirdstate to one of the other two possible states of operation.
 14. Themethod of claim 1, operating said wireless terminal in said first stateand said second state includes performing timing control signaling inboth of said states.
 15. The method of claim 14, wherein the rate atwhich timing control signals are transmitted by said wireless terminalin said first state is at least as fast as the rate at which timingcontrol signals are transmitted by said wireless terminal whileoperating in said second state.
 16. The method of claim 15, wherein inany state of operation in which power control signals are transmitted,the wireless terminal transmits said power control signals at a rate noslower than the rate at which timing control signals are beingtransmitted.
 17. The method of claim 14, wherein timing correctionssignals include timing control messages, the timing control messagesbeing transmitted at non-regular time intervals.
 18. The method of claim1, wherein operating said wireless terminal in at least two of saidthree states includes receiving timing correction signals from the basestation in a communications channel segment dedicated to said wirelessterminal to the exclusion of use of said communication channel segmentby other wireless terminals.
 19. The method of claim 1, wherein saidmethod further includes operating the base station, operating said basestation including: controlling the base station to allocate, over atleast one one-second time period, more downlink communications resourcesused to communicate user data from the base station to wirelessterminals in said cell which are in the first state, than which are insaid second state.
 20. The method of claim 19, wherein user data doesnot include power control and timing control signals.
 21. The method ofclaim 1, wherein said wireless terminal is allocated at least somedownlink data channel segments during said second state, the step ofoperating said wireless terminal in said second state including:receiving at least some user data, transmitted in said at least somedownlink data channel segments, from said base station.
 22. The methodof claim 21, wherein said wireless terminal is allowed no uplink trafficchannel data segments which can be used to transmit user data while saidwireless terminal is in said second state.
 23. The method of claim 1,wherein said method further includes operating a base station, includedin the same cell as said wireless terminal, to control transitions ofsaid wireless terminal between at least two of said three states as afunction of quality of service profile information associated with saidwireless terminal.
 24. The method of claim 23, wherein said base stationfurther controls transitions of said wireless terminal between at leasttwo of said three states as a function of traffic quality of serviceprofile information associated with said wireless terminal.
 25. Themethod of claim 1, wherein operating said wireless terminal furtherincludes: controlling transitions of said wireless terminal between atleast two of said three states as a function of quality of serviceprofile information associated with said wireless terminal.
 26. Awireless terminal, comprising: means for controlling said wirelessterminal to operate, at different times, in each one of at least threedifferent operational states, the three different operational statesincluding an first state, a second state and a third state; means forcommunicating with a base station, during said first state of operation,using a first amount of a control communications resource used to sendcontrol signals between the base station and said wireless terminal;means for communicating with the base station, during said second stateof operation, using a second amount of said control communicationsresource, said second amount of said control communications resourcebeing less than said first amount, said used second amount of saidcontrol communications resource including a dedicated uplink signalingchannel and a shared downlink signaling channel used to communicateinformation relating to the allocation of uplink and downlink resourcesfor the communication of data, respectively; and means for communicatingwith the base station, during said third state of operation, using athird amount of said control communications resource which is less thansaid first and second amounts.
 27. The wireless terminal of claim 26,further comprising: a user input device; and means for controllingtransitions from one of said three states to another one of said threestates in response to user input received from said user input device.28. The wireless terminal of claim 27, wherein said first state is an onstate, said second state is a hold state, and said third state is asleep state.
 29. The wireless terminal of claim 36, wherein said thirdamount of control communications resource includes a third set ofcommunications elements, which said second amount of controlcommunications resource includes a second set of communications elementswhich includes additional communications elements in addition to saidthird set of communications elements, and where said first amount ofcontrol communications resource includes a first set of communicationselements which includes said second set of communications elements inaddition to said second set of communications elements.
 30. The wirelessterminal of claim 29, wherein the communications elements of segments ofcontrol channels.